#include<stdio.h>
#include<string.h>
int factorial(int n)
{
    if(n==1)
        return 1;
    else
        return n*factorial(n-1);
}


int MyStrlen(char *s)
{
    if(*s=='\0')
        return 0;
    else
        return 1+MyStrlen(++s);
}

int Monkey_and_Peach(int day)
{
    if(day>=10)
        return 1;
    else
        return (Monkey_and_Peach(day+1)+1)*2;
}

int main()
{   
    printf("%d\n",factorial(10));
    printf("%d\n",MyStrlen("hello"));
    printf("%d\n",Monkey_and_Peach(1));
}